The invention relates generally to healthcare applications, and more particularly to sensors in medical monitoring.
Various medical procedures require continued monitoring of patients. For example, when the patients are unable to take care of themselves, the patients may be monitored using a variety of monitoring devices (e.g., by remote monitoring) to ensure their well-being. This kind of monitoring may be for the bed-ridden patients or for the mobile patients as well. Such devices may monitor, ventilation, oxygenation, metabolism, blood circulation, electrocardiography (ECG), and electroencephalography (EEG). ECG devices monitor the activity of the heart, whereas EEG devices monitor the activity of the brain. Both ECG and EEG employ sensors that can pickup electrical signals from the corresponding organs in the body. These electrical signals are generally low level. For example, the electrical signal from the heart is about 0.5 milli volts to 2 milli volts, and the signal from the brain is a few hundred microvolts. Accordingly, it is desirable to have optimum skin preparation and electrode placement to avoid weakening and artifacts of these signals at the skin-electrode interface. A good contact between the sensor and the skin is desirable for good signal acquisition. Failure to have a good or continuous contact between the sensor and the skin can cause signal loss. Also, failure to securely attach the sensor to the skin can introduce artifacts into the signals. These artifacts may cause the system to generate false calls or suspend analysis.
In conventional sensors, adhesive materials are used to couple the electrodes to the skin. Depending on the application, the adhesives may vary in shape and tack strength. As used herein, the term “tack strength” refers to “stickiness” of adhesive material, and is a measurement of the strength of adhesion. For short-term ECG recordings (few seconds), the electrodes may be smaller and need not employ high strength adhesive because the patient will generally be still during this short period. However, the adhesive material, such as an adhesive gel, employed to couple the electrode to the skin, may dry out during the recording. Therefore a technician is required to continuously monitor and, if required, repair any electrode dislocations. For long term recordings, the electrode is more likely to suffer from disturbances caused by tugging, jostling, inadvertent scratching, clothing changes. During these disturbances the electrode may be inadvertently detached from the skin and coupling the electrode again to the skin using the same adhesive material may not have desirable results. Moreover, sudden detachment of the electrode may injure the patient. Adhesive materials may also cause rashes or other skin irritations. Adhesives may also cause injury and pain when the sensor is removed from the skin. For example, in neo-natal applications, removing sensors from the soft skin of a newborn without injuring the skin is difficult at best.
Accordingly, it is desirable to have a sensor that may be easily coupled and detached from the skin and which is configured to attach to the skin for extended period of time.